石墨基体表面原位生成的TiB2-C涂层结构研究

The structure of an in-situ formed titanium-boron-carbon coating on a graphite substrate

  • 摘要: 通过将二硼化钛置于石墨基体表面并加热至共熔温度以上,在石墨基体表面原位生成了TiB2-C涂层。所形成的涂层表面为石墨,内部为TiB2-C合金。由于二硼化钛与石墨间热膨胀系数的不同,致使涂层表面的石墨有许多褶皱;内部的TiB2-C合金为三维贯穿结构,其中的石墨组分d002值为0.335 6 nm,接近于单晶石墨的0.335 4 nm,拉曼光谱及XPS结果表明石墨晶格中有B原子的掺杂。热震试验表明此种原位生成的涂层与基体具有良好的结合力,该方法有望成为碳材料表面制备热防护涂层的新途径。

     

    Abstract: A titanium-boron-carbon coating was fabricated on a graphite substrate by heating TiB2 powder on a graphite surface above the eutectic temperature. The coating consisted of a pure graphite layer on the outer surface and a TiB2-C alloy layer inside. The graphite layer had many wrinkles due to the difference in the thermal expansion coefficients of TiB2 and graphite. The TiB2-C alloy layer had a continuous three-dimensional interpenetrating network microstructure. The d002 value of the graphite in the alloy layer was 0.335 6 nm, which was quite close to that of single crystal graphite (0.335 4 nm). Raman and X-ray photoelectron spectroscopy indicated that the graphite in both layers was doped substitutionally with boron atoms. A water quench thermal shock test verified a high adhesion strength between the coating and the substrate. This method is promising for the fabrication of thermal barrier coatings on carbon materials.

     

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